Today, there is widespread interest in conserving non-renewable natural resources and, in particular, in improving the fuel efficiency of vehicles powered by internal combustion engines. Since approximately two-thirds of the fuel energy in internal combustion engines is dissipated as heat to the exhaust and coolant systems, there is interest in recovering at least a fraction of this wasted thermal energy to do useful work and improve vehicle fuel economy. The relatively low temperature of this dissipated heat has been a deterrent to its exploitation since standard energy recovery techniques have not been sufficiently efficient in this regard.
It is an object of the present invention to provide an energy recovery apparatus and method including multiple series of shape memory elements having different transformation temperatures for use in a manner to directly and indirectly recover thermal energy from a relatively low temperature fluid flow, such as, for example, waste exhaust gases of an internal combustion engine.
It is another object of the present invention to provide an energy recovery apparatus and method including multiple series of shape memory elements having different transformation temperatures for use in a manner to directly and indirectly recover thermal energy from a relatively low temperature fluid flow over a substantial range of fluid temperatures down to a near-ambient temperature level where the fluid is exhausted to ambient, thereby improving the efficiency of energy recovery from the fluid flow.